The present invention relates to the field of locks and more particularly to a control device with redundancy for fitting to a lock of an access door to a protected place, the device being adapted to manage a change of state of the lock and to maintain this state current.
In general terms there are three types of locks for fitting to an access door of a place protected by an enclosure, such as a strong box and a strongroom: time locks, combination locks and delayed action locks. There are furthermore locks arranged to implement the functions of time locks, combination locks and delayed action locks.
By way of example, FIG. 1 shows a conventional electromagnetic lock comprising a mechanism 1 for locking and unlocking an access door of the type mentioned above, by way of a bolt 3 of this lock. The mechanism 1 is controlled by an electronic control device 2 and is connected mechanically to the bolt 3. The mechanism 1 is designed to block the bolt 3 in a certain position (typically in the locking position) for a predetermined duration defined by the control device 2. The control device 2 comprises release means 4 for instructing a change of state of the lock and control means 5 for effecting this change of state. To this end, the release means 4 are electrically connected to the control means 5, which are mechanically connected to the mechanism 1 in such a way that the release means 4 can provide a request for a change of state of the lock to the control means 5 and that the control means 5 can command the mechanism 1 to make this change, i.e. the locking or unlocking of the access door. The control device 2 further comprises a clock mechanism formed essentially by an internal clock 6 for defining the elapse of real time and by a memory 7 for storing information provided by an external user by way of a user interface 8. Furthermore the user interface 8 comprises display means (not shown in FIG. 1) for providing the external user with information relating to the operation of the control device 2.
A fair number of electronic control devices have been proposed to ensure optimum security of places to be protected. The control devices used most often rely on the principle of redundancy applied to the electronic components which they employ, so that, in the case of failure of one of the electronic components, the other electronic component can ensure unlocking and locking of the access door, in order to avoid destructive external intervention on the door or its lock, and to maintain the protection of the assets.
The patent BE 874 278 describes a combination control device for opening an access door of the type referred to. FIG. 2 of the present description shows such a device which will be denoted by the reference 10.
The device 10 comprises a keyboard 11 allowing combinations to be entered and two identical assemblies 12 and 12xe2x80x2. The assembly 12 comprises a first memory 13 containing the combination which allows the lock to be released, a second memory 14 arranged to receive the combination entered by way of the keyboard 11 by the person desiring to release the lock, first means 15 arranged to compare the combination contained in the first memory 13 with the combination entered in the second memory 14, and second means 16 arranged to cause the lock to be released when it receives an appropriate signal from the first means 15. The elements of the electronic assembly 12xe2x80x2 are identical to the corresponding elements of the assembly 12 and carry the same references as the latter, supplemented with a prime.
The principle of redundancy has also been applied to mechanical components, for example in time locks. By way of example, French patent application published under the No. 2 661 938 in the name of CIPOSA MICROTECHNIQUES describes a lock fitted with a control device comprising two similar mechanical time movements. Typically the same duration of locking the access door is given to these two movements in the evening, so that at least one of the movements controls the unlocking of the access door the following morning.
However, the applicant of the present invention has appreciated that such duplication of equipment does not provide a satisfactory solution to guaranteeing the unlocking and locking of the access door under predetermined conditions.
Thus, consider the case in which the lock of a strong box fitted with the device 10 of FIG. 2 is subject to a disturbance, which may be a change in temperature or humidity for example, resulting from an adjacent industrial activity or an atmospheric effect. Such a disturbance then has the same effect on the assembly 12xe2x80x2 as on the assembly 12. In other words, simple duplication of the components of the device 10 does not enable a very high reliability of the device to be achieved.
Consider now the case in which the assemblies 12 and 12xe2x80x2 are formed by electronic components which come from the same batch of faulty components. Thus these two components provide identical signals but these are not necessarily representative of a behaviour initially desired by the programmer. Once again, simple duplication of the components of the device does not enable a very high reliability of the device to be achieved.
Consider finally the case in which duplicated assemblies such as the assemblies 12 and 12xe2x80x2 comprise processing units programmed according to the same program. Thus the two units have identical behaviour, in particular in the case in which the said program includes programming errors. Once again the simple duplication of the components of the device 10 does not enable a very high reliability of the device to be achieved.
One object of the present invention is to provide a control device with redundancy for fitting to a lock, which device alleviates the problems mentioned above.
Another object of the present invention is to provide such a control device which can be adapted to different types of lock.
Another object of the present invention is to provide such a control device which has optimum immunity to disturbances.
Another object of the present invention is to provide such a control device meeting the needs of expense, simplicity and size.
These objects as well as others are met by the control device with redundancy according to claim 1.
One advantage of the two units lies in that these two units have two different structures and two different modes of functioning and that each electronic unit can detect faulty function of the other unit and initiate, under certain conditions, a procedure for reestablishing functioning in a normal situation of the disturbed control device, which gives the control device an optimum immunity to the disturbances.
Thanks to other characteristics of the control device with redundancy according to the present invention, one advantage of the two electronic units is that they can be programmed in accordance with two different programs respectively, which prevents the occurrence of an undesired unlocking or locking, in contrast to the conventional devices referred to above, in which the two units are provided with the same program, yielding the same command under the same conditions of execution of this program.
Thanks to other characteristics of the control device with redundancy according to the present invention, an advantage of the intermediate unit of this control device is acting as an intermediary during a transfer of data between the said electronic units, each electronic unit being able to access the intermediate unit selectively, which ensures excellent immunity from disturbances for this control device.
Thanks to other characteristics of the control device with redundancy according to the present invention, an advantage of the static supervisory signals of this control device is to provide for precision checking of the level of each static signal, which allows the activity to be checked at the time and thus gives this control device a high level of immunity to noise compared operation on the basis of dynamic signals.
Thanks to other characteristics of the control device with redundancy according to the present invention, an advantage of the control system with redundancy of this control device is avoidance of needless triggering of the emergency system, when the control system is capable of reestablishing itself in the normal functional situation of the control device.